In 2013, there were 2,716 public water supply systems in Missouri. In the previous post, I reported that 95.3% of the population received water from suppliers that had no violations of safe drinking water standards during the year (an decrease from 95.7% in 2012).
This means that 4.7% of the population was served by systems that did have a violation (down from 4.3% in 2011). As Missouri’s population in 2013 was 6,044,917, that means that 284,111 people were served water systems that had a violation during the year. This post looks into the nature of the violations.
Two years, 2007 and 2010, had an increase in the population affected by a violation. The cause in 2007 was an error in backwashing a filter at the Missouri American Water Company South Plant in St. Louis County. The error caused a spike in turbidity that lasted four minutes. During that time the water reached an estimated 24,578 customers, though no reports of illness were associated with this event. Even though only some customers were affected, federal documentation rules require that the entire service population be reported as exposed. In 2010, “the same phenomenon happened again.” (2012 Annual Compliance Report of Missouri Public Drinking Water, p. 4)
A violation does not indicate that public health was affected, but it creates the potential for a public health impact to occur. For this reason, violations are important administrative markers. The DNR monitors two broad kinds of violations. Water contaminants (chemicals and bacteria) can exceed their respective maximum concentration levels (health-based standards), or a water system can fail to meet adequate administrative standards (most often not performing and reporting the testing required by law).
The graph at right shows the percentage of the population served by community water systems that had different types of health-based violations during the year. As in most years, the most common violation in 2013 had to do with coliform bacteria. Coliform bacteria are a class of many microorganisms that are widespread in the environment. Most do not represent a hazard to human health. However, either the presence of E. Coli, a specific type of coliform bacteria, or of fecal coliform bacteria is a sign the water may have become contaminated with fecal material, which is hazardous to human health. Thus, the presence of either is a violation, and it results in a boil order. All water systems in Missouri are required to test for E. Coli and coliform bacteria, and most violations result from improper testing and/or reporting. However, 18 water systems in Missouri (less than 1%,) received boil orders in 2013, a decrease from 19 in 2012 and from 32 in 2011. Most lasted for a few days up to two weeks, but some lasted for several months. None were repeats from 2012. See the report for details.
Sixteen systems had chemical violations, almost all for trihalomethanes (down from 17 systems in 2012 and 21 systems in 2011). Trihalomethanes are water treatment byproducts. They form if disinfectants used to treat the water (chlorine, bromine) react with matter that may be present in the water (e.g. decaying vegetation).
Thirteen systems had violations involving excess radiological contaminants (down from 14 systems in 2012 and 16 systems in 2011). The problems came from several radiological elements, see the report for full details.
In 2013, 7 water systems had Surface Water Rule violations, down from 17 in 2012. Almost all of the violations were for combined filter effluent turbidity. Systems must filter surface water to remove cryptosporidium, a parasite that causes diarrhea, and a violation of the turbidity rule means the filtering may not be adequate to remove the parasite. Plattsburg had violations in both 2012 and 2013, and Maysville had violations for several months for each year!
As noted above, some of violations can be quite brief, and the threat they represent to public health can be small. However, the DNR puts a special focus on water systems that repeatedly fail to meet monitoring standards, and on those with a routine sample that tests positive for coliform, but which fail to submit follow-up or repeat samples as required.
Twenty-seven water systems were listed as having had three or more major monitoring violations in 2013 (down from 31systems in 2012 and 44 systems in 2011). Many of them were in violation for many months (some for the whole year). The list, Appendix B, is shown at right.
In addition, 43 water systems had water that tested positive for excess coliform bacteria, but failed to provide required follow-up samples for testing. (This represents and increase from 30 systems in 2012 and 34 systems in 2011.) The list, Appendix C, is shown at right.
Missouri Department of Natural Resources. 2013 Annual Compliance Report of Missouri Public Drinking Water Systems. http://dnr.mo.gov/pubs. Published 2014-11-18. This URL will take you to a long list of publications available from MoDNR. Scroll down to Public Drinking Water to find the compliance reports.
Missouri Department of Natural Resources. 2012 Annual Compliance Report of Missouri Public Drinking Water Systems. http://dnr.mo.gov/pubs. Published 2014-11-18. This URL will take you to a long list of publications available from MoDNR. Scroll down to Public Drinking Water to find the compliance reports.
EPA. Long Term 1 Enhanced Surface Water Treatment Rule Turbidity Provisions: Technical Guidance Manual. http://water.epa.gov/lawsregs/rulesregs/sdwa/mdbp/upload/2004_11_22_mdbp_lt1eswtr_guidance_lt1_turb.pdf.
United States Census Bureau. State and County Quick Facts: Missouri. http://quickfacts.census.gov/qfd/states/29000.html.